Field of the Invention
The invention relates to a drilling unit apparatus and more particularly to drilling unit apparatus of the type having
a housing; PA1 a drilling spindle housing means axially moveable within said housing; PA1 a drilling spindle rotatably received within said housing and driven by a driving means; PA1 a plunger connected to the drilling spindle housing means and adapted to move axially with the drilling spindle housing means within said housing; PA1 piston means slideably received within said housing and operatively connected to the plunger to move it in upward or downward direction respectively.